It is known in the transmission art to first synchronize and clutch an intermediate shaft or ratio gear with the transmission output and to then clutch the intermediate shaft or ratio gear to the transmission input. Such synchronizing, which may be referred to as output synchronizing, is also known in prior art transmissions having plural countershafts. Many prior art transmissions, which employ plural countershafts and output synchronizing, power shift from one countershaft to another to upshift or downshift the transmission and synchronize a non-driving countershaft with the transmission output in preparation for the next shift.
When the above prior art transmissions are used in combination with a torque converter, the sole source of power input to the transmission is through the torque converter which is rather inefficient and not needed in the higher speed ratios of the transmission. To negate this inefficiency, torque converter bypass or lock out clutches have been used. Such clutches have the disadvantage in that they and their needed control systems may increase the cost and complexity of the transmissions.